<!DOCTYPE html>
<p>We have a multicol with an absolutely positioned multicol child. That child has a spanner inside. The absolutely positioned multicol child isn't part of its parent multicol, since it's out of flow. The absolutely positioned multicol also has column-span:all, but it doesn't apply, since it's out of flow. Now make it statically positioned. That will turn it into a spanner in the parent multicol. At the same time, change it from multicol to regular block. It will still be a spanner, but since it's no longer multicol, its child spanner can no longer be one, since you cannot nest spanners in the same multicol context. So you end up with a multicol with a spanner with a regular (invalid spanner) block.</p>
<p>Below there should be four squares stacked vertically, in the following order: hotpink, yellow, papayawhip, olive.</p>
<div style="-webkit-column-count:3; -webkit-column-gap:0; width:50px; background:olive;">
    <div style="height:150px; background:hotpink;"></div>
    <div id="elm" style="position:absolute; -webkit-column-count:3; -webkit-column-span:all; padding-top:50px; background:yellow;">
        <div style="-webkit-column-span:all; height:50px; background:papayawhip;"></div>
    </div>
    <div style="height:150px;"></div>
</div>
<script>
    document.documentElement.offsetTop;
    var elm = document.getElementById("elm");
    elm.style.position = "static";
    elm.style.webkitColumnCount = "auto";
</script>
